S. Rivallant - Profile on Academia.edu (original) (raw)
Papers by S. Rivallant
A comparison of three wood species (poplar, birch and oak) for crash application
European Journal of Wood and Wood Products
Combined shear/compression structural testing of asymmetric sandwich structures
Experimental Mechanics, 2004
Stacking sequence optimization of composite tubes submitted to crushing using the discrete ply model (DPM)
Mechanics of Advanced Materials and Structures
OATAO is an open access repository that collects the work of Toulouse researchers and makes it fr... more OATAO is an open access repository that collects the work of Toulouse researchers and makes it freely available over the web where possible.
Crashworthiness of poplar wood veneer tubes
International Journal of Impact Engineering
This paper presents a study on the mechanisms leading to permanent indentation in composite lamin... more This paper presents a study on the mechanisms leading to permanent indentation in composite laminates subjected to low-velocity impact. A three-point bending test on laminated beams is used. During loading, matrix cracks appear. When unloading, it is shown that cracks cannot close entirely, due to debris inside matrix cracks and the formation of cusps where mixed-mode delamination occurs. The addition of all these non-closure in a laminate is assumed to be the origin of permanent indentation under impact loading. Then, a simple physically-based law of permanent indentation is proposed. This law is qualitatively tested with a three-point bending FE model and applied in a low-velocity impact FE model to predict permanent indentation. A comparison between experiments and models is presented.
Stacking sequence is an important effect in optimizing composite structures subjected to the low-... more Stacking sequence is an important effect in optimizing composite structures subjected to the low-velocity impact. This paper presents 7 out of 12 possible configurations made of 8double-ply, mirror-symmetric, quasi-isotropic, T700GC/M21 laminated plates, oriented at 0°, 90°, 45° and-45°. Thanks to discrete modelling with interface finite elements based on fracture mechanics, a finite element model simulates impact damage. The numerical simulations can well predict the impact damage observed in experiments. Comparison of stacking sequence effect in term of areas and shapes of delamination, and fibre failures are discussed.
Damage tolerance of composite structures under low-velocity impact
Dynamic Deformation, Damage and Fracture in Composite Materials and Structures
Static crushing of wood based sandwich composite tubes
Composite Structures
A new interface element connecting 3D finite elements with non-coincident nodes to simulate delamination in composite laminates
Composite Structures
Effects of dynamics and trigger on energy absorption of composite tubes during axial crushing
International Journal of Crashworthiness
The purpose of this study is to complete a previous quasi-static experimental campaign on the ene... more The purpose of this study is to complete a previous quasi-static experimental campaign on the energy absorption performance of composite tubes with the influence of the dynamic effect. Various hybr...
Combined loadings after medium velocity impact on large CFRP laminate plates: Tests and enhanced computation/testing dialogue
Composites Science and Technology
Composite Structures
Composites are known to be vulnerable to out-of-plane loading such as impact. Investigating the r... more Composites are known to be vulnerable to out-of-plane loading such as impact. Investigating the residual properties of the laminate as a function of damage detection is the main purpose of impact damage tolerance design in aeronautics. As a good alternative to experimental campaigns, numerical approaches would lead to saving of time. The model developed in Institut Clément Ader over the last years enables representation of behavior of composite laminates subjected to low velocity/low energy impactincluding permanent indentation and Compression After Impact. Damage such as permanent indentation, fiber failures, matrix cracks and delamination are taken into consideration at each step thanks to a discrete ply modelling. The work presented here deals with the use of this model to make a composite laminate design optimization according to impact damage tolerance design. A method to improve optimization by reducing computation time is also proposed, based on a "best candidates" selection.
Physical Mesomechanics
Stacking sequence is an important effect in optimizing composite structures subjected to the low-... more Stacking sequence is an important effect in optimizing composite structures subjected to the low-velocity impact. This paper presents 7 out of 12 possible configurations made of 8double-ply, mirror-symmetric, quasi-isotropic, T700GC/M21 laminated plates, oriented at 0°, 90°, 45° and-45°. Thanks to discrete modelling with interface finite elements based on fracture mechanics, a finite element model simulates impact damage. The numerical simulations can well predict the impact damage observed in experiments. Comparison of stacking sequence effect in term of areas and shapes of delamination, and fibre failures are discussed.
Advanced Composites Letters
An analytical modelling of symmetrical wrinkling is proposed : from original assumptions on displ... more An analytical modelling of symmetrical wrinkling is proposed : from original assumptions on displacements within the core, and from an energy minimisation method, it is possible to predict critical loads and buckling modes better than traditional models do, and to distinguish the influence of each structure component. Compression tests were carried out on sandwich structures to validate the model. A FE analysis has been achieved in parallel : a fine modelling allows finding results close to experimental ones.
An analytical modelling of the symmetrical wrinkling is proposed : from original assumptions on d... more An analytical modelling of the symmetrical wrinkling is proposed : from original assumptions on displacements within the core, and from an energy minimisation method, it is possible to predict critical loads and buckling modes better than traditional models do, and to distinguish the influence of each structure component. Compression tests were carried out on sandwich structures to validate the model. Little curved structures were also tested to estimate the influence of skin curvature on rupture and buckling mode. A finite elements analysis has been achieved in parallel : a fine modelling allows to find results close to experimental ones.
Acheter cet article (format PDF)
An analytical modelling of symmetrical wrinkling is proposed : from original assumptions on displ... more An analytical modelling of symmetrical wrinkling is proposed : from original assumptions on displacements within the core, and from an energy minimisation method, it is possible to predict critical loads and buckling modes better than traditional models do, and to distinguish the influence of each structure component. Compression tests were carried out on sandwich structures to validate the model. A FE analysis has been achieved in parallel : a fine modelling allows finding results close to experimental ones.
Le présent article propose une étude de l'endommagement de structures similaires à des tronçons d... more Le présent article propose une étude de l'endommagement de structures similaires à des tronçons de pales d'hélicoptère soumises à un impact. Il s'agit de structures composites complexes, fabriquées au laboratoire, et impactées par un projectile de 125 g à des vitesses d'impact de 130 m/s. Les essais sont analysés grâce à une acquisition des déformations au cours de l'essai et à une expertise post-mortem de l'éprouvette. Cela a permis de mettre en évidence les différents mécanismes d'endommagement de l'éprouvette. Un travail de modélisation est aussi présenté. Différentes stratégies de modélisation sous éléments finis, à l'échelle macroscopique, permettent ainsi de modéliser ces phénomènes avec des densités de maillage qui ne sont pas pénalisantes lors d'un calcul sur une structure réelle.
Cette étude a pour but d'améliorer la compréhension du phénomène de flambement local de peaux sta... more Cette étude a pour but d'améliorer la compréhension du phénomène de flambement local de peaux stabilisées par mousse, ainsi que la prédiction des forces et modes de flambage. Une campagne d'essais a été menée sur des éprouvettes de diverses géométries, en compression pure. Une analyse par éléments finis menée parallèlement permet, par une modélisation fine, de retrouver les valeurs expérimentales avec une bonne précision. Une modélisation analytique du wrinkling symétrique est également proposée. A partir d'hypothèses originales sur les déplacements au sein de la mousse, et d'une méthode de calcul fondée sur la minimisation des énergies, elle permet de prédire les forces critiques mieux que les modèles classiques, tout en distinguant l'influence de chaque constituant de la structure. Cette modélisation est également validée par une étude éléments finis, et donne des résultats plus précis que les modèles classiques.
A comparison of three wood species (poplar, birch and oak) for crash application
European Journal of Wood and Wood Products
Combined shear/compression structural testing of asymmetric sandwich structures
Experimental Mechanics, 2004
Stacking sequence optimization of composite tubes submitted to crushing using the discrete ply model (DPM)
Mechanics of Advanced Materials and Structures
OATAO is an open access repository that collects the work of Toulouse researchers and makes it fr... more OATAO is an open access repository that collects the work of Toulouse researchers and makes it freely available over the web where possible.
Crashworthiness of poplar wood veneer tubes
International Journal of Impact Engineering
This paper presents a study on the mechanisms leading to permanent indentation in composite lamin... more This paper presents a study on the mechanisms leading to permanent indentation in composite laminates subjected to low-velocity impact. A three-point bending test on laminated beams is used. During loading, matrix cracks appear. When unloading, it is shown that cracks cannot close entirely, due to debris inside matrix cracks and the formation of cusps where mixed-mode delamination occurs. The addition of all these non-closure in a laminate is assumed to be the origin of permanent indentation under impact loading. Then, a simple physically-based law of permanent indentation is proposed. This law is qualitatively tested with a three-point bending FE model and applied in a low-velocity impact FE model to predict permanent indentation. A comparison between experiments and models is presented.
Stacking sequence is an important effect in optimizing composite structures subjected to the low-... more Stacking sequence is an important effect in optimizing composite structures subjected to the low-velocity impact. This paper presents 7 out of 12 possible configurations made of 8double-ply, mirror-symmetric, quasi-isotropic, T700GC/M21 laminated plates, oriented at 0°, 90°, 45° and-45°. Thanks to discrete modelling with interface finite elements based on fracture mechanics, a finite element model simulates impact damage. The numerical simulations can well predict the impact damage observed in experiments. Comparison of stacking sequence effect in term of areas and shapes of delamination, and fibre failures are discussed.
Damage tolerance of composite structures under low-velocity impact
Dynamic Deformation, Damage and Fracture in Composite Materials and Structures
Static crushing of wood based sandwich composite tubes
Composite Structures
A new interface element connecting 3D finite elements with non-coincident nodes to simulate delamination in composite laminates
Composite Structures
Effects of dynamics and trigger on energy absorption of composite tubes during axial crushing
International Journal of Crashworthiness
The purpose of this study is to complete a previous quasi-static experimental campaign on the ene... more The purpose of this study is to complete a previous quasi-static experimental campaign on the energy absorption performance of composite tubes with the influence of the dynamic effect. Various hybr...
Combined loadings after medium velocity impact on large CFRP laminate plates: Tests and enhanced computation/testing dialogue
Composites Science and Technology
Composite Structures
Composites are known to be vulnerable to out-of-plane loading such as impact. Investigating the r... more Composites are known to be vulnerable to out-of-plane loading such as impact. Investigating the residual properties of the laminate as a function of damage detection is the main purpose of impact damage tolerance design in aeronautics. As a good alternative to experimental campaigns, numerical approaches would lead to saving of time. The model developed in Institut Clément Ader over the last years enables representation of behavior of composite laminates subjected to low velocity/low energy impactincluding permanent indentation and Compression After Impact. Damage such as permanent indentation, fiber failures, matrix cracks and delamination are taken into consideration at each step thanks to a discrete ply modelling. The work presented here deals with the use of this model to make a composite laminate design optimization according to impact damage tolerance design. A method to improve optimization by reducing computation time is also proposed, based on a "best candidates" selection.
Physical Mesomechanics
Stacking sequence is an important effect in optimizing composite structures subjected to the low-... more Stacking sequence is an important effect in optimizing composite structures subjected to the low-velocity impact. This paper presents 7 out of 12 possible configurations made of 8double-ply, mirror-symmetric, quasi-isotropic, T700GC/M21 laminated plates, oriented at 0°, 90°, 45° and-45°. Thanks to discrete modelling with interface finite elements based on fracture mechanics, a finite element model simulates impact damage. The numerical simulations can well predict the impact damage observed in experiments. Comparison of stacking sequence effect in term of areas and shapes of delamination, and fibre failures are discussed.
Advanced Composites Letters
An analytical modelling of symmetrical wrinkling is proposed : from original assumptions on displ... more An analytical modelling of symmetrical wrinkling is proposed : from original assumptions on displacements within the core, and from an energy minimisation method, it is possible to predict critical loads and buckling modes better than traditional models do, and to distinguish the influence of each structure component. Compression tests were carried out on sandwich structures to validate the model. A FE analysis has been achieved in parallel : a fine modelling allows finding results close to experimental ones.
An analytical modelling of the symmetrical wrinkling is proposed : from original assumptions on d... more An analytical modelling of the symmetrical wrinkling is proposed : from original assumptions on displacements within the core, and from an energy minimisation method, it is possible to predict critical loads and buckling modes better than traditional models do, and to distinguish the influence of each structure component. Compression tests were carried out on sandwich structures to validate the model. Little curved structures were also tested to estimate the influence of skin curvature on rupture and buckling mode. A finite elements analysis has been achieved in parallel : a fine modelling allows to find results close to experimental ones.
Acheter cet article (format PDF)
An analytical modelling of symmetrical wrinkling is proposed : from original assumptions on displ... more An analytical modelling of symmetrical wrinkling is proposed : from original assumptions on displacements within the core, and from an energy minimisation method, it is possible to predict critical loads and buckling modes better than traditional models do, and to distinguish the influence of each structure component. Compression tests were carried out on sandwich structures to validate the model. A FE analysis has been achieved in parallel : a fine modelling allows finding results close to experimental ones.
Le présent article propose une étude de l'endommagement de structures similaires à des tronçons d... more Le présent article propose une étude de l'endommagement de structures similaires à des tronçons de pales d'hélicoptère soumises à un impact. Il s'agit de structures composites complexes, fabriquées au laboratoire, et impactées par un projectile de 125 g à des vitesses d'impact de 130 m/s. Les essais sont analysés grâce à une acquisition des déformations au cours de l'essai et à une expertise post-mortem de l'éprouvette. Cela a permis de mettre en évidence les différents mécanismes d'endommagement de l'éprouvette. Un travail de modélisation est aussi présenté. Différentes stratégies de modélisation sous éléments finis, à l'échelle macroscopique, permettent ainsi de modéliser ces phénomènes avec des densités de maillage qui ne sont pas pénalisantes lors d'un calcul sur une structure réelle.
Cette étude a pour but d'améliorer la compréhension du phénomène de flambement local de peaux sta... more Cette étude a pour but d'améliorer la compréhension du phénomène de flambement local de peaux stabilisées par mousse, ainsi que la prédiction des forces et modes de flambage. Une campagne d'essais a été menée sur des éprouvettes de diverses géométries, en compression pure. Une analyse par éléments finis menée parallèlement permet, par une modélisation fine, de retrouver les valeurs expérimentales avec une bonne précision. Une modélisation analytique du wrinkling symétrique est également proposée. A partir d'hypothèses originales sur les déplacements au sein de la mousse, et d'une méthode de calcul fondée sur la minimisation des énergies, elle permet de prédire les forces critiques mieux que les modèles classiques, tout en distinguant l'influence de chaque constituant de la structure. Cette modélisation est également validée par une étude éléments finis, et donne des résultats plus précis que les modèles classiques.